1. Field of the Invention
This invention relates to apparatus used in connection with the formation of mat surfaces used in various settings. More specifically, this invention relates to a device, namely a mat lock pin, used to connect mats or mat features to one another, to form a structural, load-bearing surface, commonly used for roadways, work locations, etc.
2. Related Art
Relatively large, load bearing mats are used in a number of industrial settings to provide a firm surface for machinery, vehicles, etc. While various materials are used to build the mats, in many cases such mats are made of rigid polymeric plastic materials. There is a limit to the size in which such mats can be made, so in order to create a relatively large surface a number of such mats must be joined together. Since the mats are reusable, it is desirable to join the mats in a releasable fashion. The mats are frequently made with lips along one or more edges. Such lips, referred to herein as “mat features” (which may take various other configurations) are overlapped, and holes in the lips of adjacent mat features can be aligned.
It can be appreciated that the mat lock pin must sustain both lateral forces (that is, from the mats tending to move away from one another within the same plane, generally substantially horizontal) and axial forces, which are needed to force the mat features together (literally “squeeze” the mat features together). FIG. 1A is a simple schematic showing the general directions of the lateral (denoted as “L”) and axial (denoted as “A”) forces as those terms are used in this patent application.
Known prior art fastening devices, for example that disclosed in U.S. Pat. No. 6,722,831 (the '831 patent), do provide both lateral and axial forces, but do so in a different manner than the instant invention. In particular, known prior art fastening devices as disclosed in the '831 patent rely on the body of the fastening device (called a “pin body” in that patent), in conjunction with a footed rod (extending through the pin body) to provide the required axial joining force. This requires that the pin body be of sufficient strength to carry the axial force, resulting from a combination of the size (namely, the cross sectional area) and strength of the material forming the pin body. Suffice to suggest that this prior art design requires a pin body of high strength, resulting from a relatively large cross sectional area and a relatively high strength material. Both of these attributes result in a relatively high cost for the pin body component of the fastening device. In addition, the dimensional requirements for the pin body result in the rod (which extends through the pin body) being limited as to its cross sectional area, therefore a relatively high strength (and high cost) material must also be used for that element of the fastening device to yield the required axial strength.
The present invention addresses certain of the limitations of the known prior art fastening devices.